1. Field of the Invention
The present invention concerns a method for detection of a stable installation (setup) of a system of the type having a rotation device that rotates around a system axis and a detection arrangement for measurement values of oscillation (vibration) of the rotation device. The invention moreover concerns a method for detection of a stable installation of a computed tomography system as a part of a method for correction of an out-of-balance state of the gantry thereof.
2. Description of the Prior Art
In apparatuses with rapidly rotating masses, an existing out-of-balance condition, or an out-of-balance condition that occurs in the course of the operation, lead to a series of unwanted events. These range from oscillations of the overall system to excessive bearing wear and, in medical apparatuses, to interferences in the generation of images, such as in medical tomography apparatuses.
A tomography apparatus of this type is, for example, a computed tomography apparatus with a rotation device in the form of a gantry, the rotation device being mounted to rotate around the system axis. An out-of-balance state can be caused, for example, by installation tolerances of the components on the gantry.
For detection and correction of an existing out-of-balance condition or an out-of-balance condition that occurs during the operation of the computed tomography apparatus from DE 101 08 065 A1 discloses an arrangement for detection of measurement values of an oscillation of the gantry caused by an out-of-balance situation. At least one point on the gantry at which a weight should be arranged for compensation of the out-of-balance state is determined from the detected measurement values.
The detected measurement values are influenced not only by the out-of-balance situation of the gantry itself but also by the oscillation behavior of the overall system. The measurement values can be significantly disturbed given an unstable installation of the computed tomography apparatus. An incorrect installation during the start-up can lead, for example, to the situation that the overall system additionally exhibits a barely perceivable tilt movement during the rotation of the gantry.
The location at which a weight should be arranged for compensation of the oscillation behavior in such a case is incorrectly determined on the basis of the disturbed measurement values. Even for experienced service personnel, it is not possible to correct the out-of-balance condition sufficiently well by an arrangement of weights on the gantry without correction of the installation of the computed tomography apparatus, even with multiple repetitions of the correction process.